Nothing like using equipment that’s simultaneously obsolete and on the bleeding edge..

So, today the cogging problem returned to the EV drive. Mercifully, it doesn’t seem to have extended to actually setting fire to the power stage (yet.. knock on wood) but things are definately broken. I had hoped the problem was the current/voltage limit, but since it is still doing it fully charged, that seems unlikely. At the moment I’m inclined to blame a faulty rotation encoder, the encoder wiring, the encoder input system on the inverter, or a bug in the inverter software. Also possible is that there’s some current leaking somewhere it shouldn’t.

I don’t even know where to start in debugging this. I’m somewhat depressed about it. I emailed Metric Mind, the people who originally sold me the drive, and I’m hoping they will have some helpful hints. I’m going to get the car back in the garage, up on jackstands again, and thoroughly clean out the inside of the motor access plate – not that I think it’s dirty, but it’s something to do. I’m also going to take contuninity readings of the encoder cable.. again, not that I think it’s broken, but it’s something to do. There aren’t really any tunable parameters on the inverter that I see that could be causing this cogging – I had thought it was just because I was operating the drive in reverse, but it seems to exist going forward, too.

This problem started when I swapped out the Evercel battery pack for the lead acid one. I’m trying to think what changed.. pack voltage, obviously.. probably the stiffness of the pack, since lead acid doesn’t sag as much as NiZn.. I redid the cooling loop, but I don’t see how that would have anything to do with anything.. unless.. there is a tiny coolant leak next to the motor. I *assume* those heatsinks are isolated.. but maybe I should stop assuming and start fixing… again, it’s something I can do..

A lot of what’s frustrating is that there’s very little documentation for the system – Victor of Metric Mind has done a great job documenting, but there’s still a whole lot of variables that I don’t have any way of guessing. I bought the drive because I thought it would be bulletproof – after all, Siemens makes industrial drives all over the place, and they generally just work. If this drive doesn’t work out, do I try and get another? without the assistance of a community college’s shop, I don’t see how I could hope to swap drives.. although, it’s true that I wouldn’t *need* a lift.. then there’s the money question – how do I pay for another drive? – and the engineering challenges, which nearly drove me nuts last time.

On the other hand, I’ve learned a lot.. if I tried again, it might come out much better. And there’s always the hope that Metric Mind will send me a firmware update that will fix everything, or something..

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